Intake air filter for an internal combustion engine

ABSTRACT

A filter device, especially an intake air filter for internal combustion engines, comprises a cylindrical filter housing (1) with inlet and outlet openings (7, 6) for the medium. In the outlet opening (6), a pipe stub (11) is fixed with the aid of an elastic sleeve (12), which forms a seal between the opening edge (14) and the stub and between the stub and an intake conduit (15) coupled thereto. The pipe stub has a portion (11a) extending into the filter housing, against which portion (11a) there seals a radial seal (17) on a filter element (2) enclosed in the housing.

The present invention relates to a filter device for filtering a gaseousmedium, comprising a filter housing with an inlet opening and an outletopening for the medium, a filter element enclosed in the housing anddisposed between said openings, and a pipe stub coupled to the outletopening of the housing for coupling to a gas conduit, said pipe stubextending through the outlet opening and having a portion extending intothe interior of the housing, which portion has a surface which can forma sealing surface against a seal on the filter element.

A common type of air filter for internal combustion engines has acylindrical filter housing with the outlet opening at one end. The pipestub for connecting the filter to an intake conduit is fixed to thehousing end plate and the filter element, which typically has a tubularfilter body, abuts with one end against the end surface surrounding theoutlet with a seal therebetween, which is compressed when the filterbody is pressed against the outlet end plate by the other end plate ofthe housing, which serves as a cover when in place.

These axially sealing filters have a major disadvantage. Due to the factthat the filter must be fitted between the housing end plates, specialattention must be paid to the axial dimension of the filter element andthe filter housing. Any deviations can result in leakage or damage tothe filter element.

A known solution to this problem is to seal the filter element radially.The filter element is provided on its inner lateral surface at itsoutlet end with a radial sealing ring, which seals against the pipe endforming an extension of the outlet stub extending into the filterhousing. Thus the only requirement as to axial fit is that the filterseal must enter the stub.

The requirement of a pipe end extending into the filter housing, againstwhich the filter element seals, creates, however, production technicalproblems. For instance, an inwardly directed cylindrical surface cannotbe produced by blow moulding of the housing. A solution to this problem,which is described in U.S. Pat. No. 4,720,292, for example, is to makethe outlet stub separately from the filter housing and to fix it to theoutlet end plate in such a manner that the end portion of the outletstub extends into the filter housing.

The purpose of the present invention is, starting from the knownsolution mentioned above, to achieve a filter device of the typedescribed by way of introduction which is simple to manufacture andassemble and which provides a good stress distribution between theoutlet stub and the filter housing as well as providing an effectiveseal between the stub and an intake conduit coupled thereto.

This is achieved according to the invention by virtue of the fact thatan elastic angular element is placed between the edge of the outletopening and the outer surface of the pipe stub and extends axially outover the pipe stub to form a seal between the pipe stub and a gasconduit coupled thereto.

According to a preferred embodiment of the filter device according tothe invention, the elastic angular element is provided on its exteriorwith a peripheral groove, into which there extends an edge portion ofthe housing surrounding the outlet opening.

This makes assembly quite simple. An elastic element, e.g. in the formof a rubber sleeve, is folded radially, is inserted into the outletopening of the housing and is allowed to expand so that the edge portionslips into the groove. The outlet stub is then inserted into the sleevewhich is thus fixed in its expanded state. Thus a single element servesas an elastic fixing means for the pipe stub, as a vibration absorbingmeans between the intake conduit and the filter housing and as a sealingdevice between the pipe and the intake conduit as well as compensatingmeans for variations in the axial dimensions.

The invention will be described in more detail below with reference toexamples shown in the accompanying drawings, of which

FIG. 1 shows a longitudinal section through the upper half of a filterdevice according to the invention, and

FIGS. 2-4 show partial views in longitudinal section of three modifiedembodiments in the area marked II in FIG. 1.

The reference numeral 1 in FIG. 1 generally designates a filter housingand the reference numeral 2 generally designates a filter elementenclosed in the housing 1. The housing 1 consists of a cylindricalelement 3 of blow moulded plastics material, for example, with endplates 4 and 5, of which the end plate 4 forms a cover screwed onto thecylinder 3 and fixed to the filter element, whereas the end plate 5 isintegral with the cylinder 3 and has an outlet opening 5. An inlet pipe7 opens into the cylinder 3. The filter element 2 comprises a pair ofperforated coaxial cylinders 8 and 9 with an intermediate filtermaterial 10 of a type which is known per se, e.g. folded paper or steelwool.

A pipe stub 11 in plastic or metal is fixed in the housing opening 6with the aid of a sleeve 12 of rubber or a material similar to rubber.The stub 11 has a portion 11a of larger diameter than the portion 11b ofsmaller diameter and a radial wall portion 11c forming a transitionbetween the portions 11a and 11b. The sleeve 12 has a thicker portion12a and a thinner portion 12b. The radial wall serves as an abutmentsurface for the thicker end of the sleeve 12. The opposite end of thesleeve 12 extends out to the outer end of the pipe stub 11. The thickerportion 12a of the sleeve 12 has a peripheral groove 13, into which anedge portion 14 of the housing wall 5 extends. The end 15 of an engineintake conduit is forced over the sleeve portion 12b and is secured by ahose clamp 18.

The right hand end (FIG. 1) of the filter element 2 is covered by athermoplastic elastomer, e.g. PUR, which forms a cover 16 which has anangular portion 17 extending into the inner cylinder or liner 9 of thefilter element and forming a radial seal against the pipe stub portion11a. Alternatively, the component 16 can be a sheet metal cover with aseal 17 glued thereto.

When mounting the filter device 1, the sleeve 12 is first folded andinserted into the opening 6, so that the groove 13 is in alignment withthe edge portion 14, whereafter the sleeve is allowed to expand to itsoriginal shape, so that the edge portion 14 slips into the groove 13.The pipe stub 11 is then inserted from the left as seen in the Figuresuntil the radial surface 11c comes into contact with the left hand endof the sleeve. The subsequent securing of the intake conduit end 15 tothe sleeve 12 results in the housing 1, the pipe stub 11, the sleeve 12and the conduit end 15 being secured in relation to each other. Theelasticity of the thicker portion 12a of the sleeve 12, however,provides a certain amount of relative movement between the pipe stub 11and the housing end plate 5 to compensate for dimensional variations,distribute stress and absorb vibrations. After installation of thefilter element 2, the sealing ring 17 helps keep the mounting of thepipe stub firm in the housing.

FIG. 2 shows a filter device according to the invention in a furtherdeveloped form. The pipe stub 11 is here permanently fixed to asecondary or safety filter 20. In other respects the embodiment agreeswith that described above and the same reference numerals have been usedas in FIG. 1 for corresponding components in FIG. 2. The secondaryfilter comprises a perforated tube 21, the right hand end of which asseen in FIG. 2 is permanently fixed to the pipe stub 11, e.g. byadhesive.

When replacing the main filter 2, the secondary filter 20 prevents dirtfrom being sucked into the engine if it should be started without themain filter in connection with service. The same applies should the mainfilter be damaged. When removing the secondary filter, the hose clamp 18around the intake conduit 15 must be removed since the outlet stub 11 isremoved with the secondary filter.

FIG. 3 shows an embodiment which differs from that shown in FIG. 1 onlyby a somewhat altered shape of the thicker portion 12a of the sleeve 12and the edge portion 14 of the housing. The groove 13 is wider and theedge portion 14 is made with an axial flange 14a. By adjusting theelasticity and the thickness of the sleeve portion 12a, the width of thegroove 13 and the shape of the edge portion 14, it is possible toregulate the angular alignment error which can be compensated forbetween the stub, the intake conduit and the filter housing, as well asthe stress distribution.

FIG. 4 shows an embodiment in which the intake conduit 15 is made in onepiece with the sleeve 12. Even though the invention was developedprimarily to solve the problem involved in radially sealing filters, asrevealed in FIGS. 1 and 2, it is obvious that a filter housing with thesleeve and pipe stub arrangement described can also be used for axiallysealed filters, in which case the outer surface of the inwardly directedflange will not be used. In this case one also enjoys the advantage ofsimple assembly, vibration absorption and sealing between the stub andthe intake conduit.

We claim:
 1. Filter device for filtering a gaseous medium, comprising afilter housing with an inlet opening and an outlet opening for themedium, a filter element enclosed in the housing and disposed betweensaid openings, and a pipe stub coupled to the outlet opening of thehousing for coupling to a gas conduit, said pipe stub extending throughthe outlet opening and having a portion extending into the interior ofthe housing with a surface which can form a sealing surface against aseal on the filter element, characterized in that an elastic angularelement (12) is placed between the edge (14) of the outlet opening andthe outer surface of the pipe stub (11) and extends axially out over thepipe stub to form a seal between the pipe stub and a gas conduit (15)coupled thereto.
 2. Filter device according to claim 1, characterized inthat the elastic angular element (12) is made in one piece with the gasconduit (15) coupled thereto.
 3. Filter device according to claim 1,characterized in that the pipe stub (11) has portions (11a, 11b) withdifferent diameters and that the elastic angular element (12) is incontact with a radial wall (11c) forming a transition between theportions with different diameters.
 4. Filter device according to claim1, characterized in that the elastic angular element (12) is provided onits exterior with a peripheral groove (13), into which there extends anedge portion (14) surrounding an outlet opening (6).
 5. Filter deviceaccording to claim 4, characterized in that the elastic angular element(12) has an end portion (12a) of larger thickness than the remainingportion (12b) and the peripheral groove (13) is disposed in said endportion.
 6. Filter device according to claim 5, characterized in thatthe larger diameter portion (11a) of the pipe stub (11) extends into thefilter housing (1) and that the end portion (12a) of the elastic angularelement with larger thickness is in contact with said radial wall (11c).7. Filter device according to claim 1, characterized in that the pipestub portion (11a) extending into the filter housing has an outersurface forming a sealing surface against the inner surface of a sealingring (17) on a cylindrical main filter element (2), and an inner surfacewhich forms a sealing surface against the outer surface of a sealingring (22) on a secondary or safety filter (20) arranged concentricallyin the main filter element.
 8. Filter device according to claim 7,characterized in that the pipe stub (11) is permanently fixed to thesecondary or safety filter (20).